1. Field of the Invention
The present invention relates to an electronic component containing substrate including a substrate, an electronic component mounted on a main surface of the substrate, and an embedment layer embedding the electronic component.
2. Description of the Related Art
With decreases in thicknesses of portable electronic devices, an electronic component containing substrate aiming to achieve a smaller thickness of a substrate by embedding an electronic component in the substrate has recently been proposed as seen in International Publication WO2011/135926.
FIG. 44 is a cross-sectional view of an electronic component containing substrate 100 described in International Publication WO2011/135926. In electronic component containing substrate 100 shown in FIG. 44, electronic components 101 and 102 are mounted on a substrate 108 and an embedment layer 109 embedding electronic components 101 and 102 is formed.
Since such electronic component containing substrate 100 is light in weight and does not involve firing at a high temperature like a ceramic substrate, restriction imposed on a contained electronic component is advantageously little.
A multilayer ceramic capacitor as electronic components 101 and 102 embedded in embedment layer 109 of electronic component containing substrate 100 described in International Publication WO2011/135926 is discussed. FIG. 45 shows a cross-sectional view of a multilayer ceramic capacitor 201.
Multilayer ceramic capacitor 201 includes a ceramic multilayer body 202 and a first external electrode 203 and a second external electrode 204 provided on a surface of ceramic multilayer body 202. Ceramic multilayer body 202 is obtained by connecting in parallel and layering capacitor elements, each capacitor element including a first internal electrode 206 and a second internal electrode 207 with a ceramic dielectric layer 205 being interposed therebetween. Such multilayer ceramic capacitor 201 achieves high reliability and durability and can realize a large capacity with a small size.
In multilayer ceramic capacitor 201 achieving a large capacity with a small size, a ceramic material having a high dielectric constant basically composed of barium titanate is often used as a material for ceramic dielectric layer 205 forming ceramic multilayer body 202. When a voltage is applied to multilayer ceramic capacitor 201 including such ceramic multilayer body 202, distortion in accordance with magnitude of an applied voltage is produced in ceramic multilayer body 202 owing to an electrostriction effect and an inverse piezoelectric effect. Accordingly, ceramic multilayer body 202 repeats expansion in a direction of layering and contraction in a planar direction perpendicular to the direction of layering.
With a decrease in size and thickness of multilayer ceramic capacitor 201 in recent years, the intensity of an electric field applied to a dielectric is also higher and a degree of distortion in ceramic multilayer body 202 has also increased.
As shown in FIG. 46A, an example in which multilayer ceramic capacitor 201 is mounted on a substrate B with the use of a connection member S is discussed. When a voltage is applied to multilayer ceramic capacitor 201, as shown in FIG. 46B, distortion produced in ceramic multilayer body 202 vibrates substrate B secured to multilayer ceramic capacitor 201 through connection member S.
Such vibration of substrate B may cause an erroneous operation of an acceleration sensor when an acceleration sensor such as a shock sensor is mounted on substrate B.
When a frequency of the vibration is from 20 Hz to 20 kHz representing an audibility range, audible sound is recognized by human ears. This phenomenon is also called “acoustic noise,” and with electronic devices becoming more silent, such a phenomenon has become a problem in design of a power supply circuit for various applications such as a notebook personal computer, a portable telephone, and a digital camera.
When multilayer ceramic capacitor 201 is mounted on substrate B with the use of connection member S as above and further embedded in the embedment layer as described in International Publication WO2011/135926, connection member S and the embedment layer may transmit distortion in ceramic multilayer body 202 to substrate B. In that case, aggravated vibration of substrate B described previously and louder audible sound are concerned.